From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
The manufacturing difficulties of Spectre Bottom Tappets due to camshaft grinding limitations.
| Identifier | ExFiles\Box 96\2\ scan0024 | |
| Date | 12th February 1935 | |
| 49 x 354 To E.{Mr Elliott - Chief Engineer} c. to Ey. c. to RHC.{R. H. Coverley - Production Engineer} SECRET Hs{Lord Ernest Hives - Chair}/Smth.9/KW.12.2.35. SpectreCodename for Phantom III Bottom Tappets. Re E/JNR.{Charles L. Jenner}1/HP.11.2.35. We understand that in connection with the scheme for roller tappets, LeC.4353, you propose to reduce the base circle diameter of the cams from 1.250 to 1.050. We are informed that it is impossible to grind a SpectreCodename for Phantom III Camshaft, with our present machines, using a grinding wheel diameter of less than 2.500. In view of this we suggest that before proceeding with LeC.4353 you should look into the possibility of producing a suitable cam form with a 1.050 base circle dia., or alternatively of modifying the scheme to accommodate larger cams. Hs{Lord Ernest Hives - Chair}/F.Ll.Smith. | ||